Bucky grid and method of making same



June 28, 1938. A. P. FREEMAN BUCKY GRID AND METHOD OF MAKING SAME Filed Dec. 4, 1937 Tim].

UIIIIIIIIIIIIIIIIIIIIIIIIIIIlIlIlIlHllll\lllll\\\\\\\\\\\\\\\\\\ INVENTOR ANTONY 1?.FEEEMAN mam i ATTORNE? Patented June 28, 1938 UNi'iED STATES PATENT @FFifiE BUCKY GRID AND METHOD OF MAKING SAlWE 4 Claims.

This application is a continuation in part of my application, Serial Number 141,511, filed May 8, 1937, entitled X-ray grid and method of making same.

- The object of this invention is to provide a Bucky grid having the properties of excluding or absorbing so-called secondary X-ray radiation. More particularly the objects of this invention are to provide an X-ray grid structure of such extreme fineness or grain that the marking left by it on a photoplate or fiuroscopic screen will be practically imperceptible when maintained in a stationary position between, a Roentgen tube and such plate or screen.

Other objects of the invention are to provide a grid for X-ray photography and like purposes which will be flat in form, capable of giving perfect focus, unusually light in weight, and simple to manufacture at low cost. Great need of a grid 20 which embodies all or even the greater part of the aforementioned characteristics is well known throughout the X-ray art and many unsuccessful attempts have been made to produce a structure of this kind.

I am aware of the fact that others have devised various means for excluding the familiar, troublesome secondary radiation, but I am not aware that any unitary structure embodies all of the characteristics claimed in my invention.

Other objects and advantages of this invention will appear as this specification proceeds and the novelty of the invention will be particularly pointed out in the appended claims.

In the accompanying drawing,

Figure l is a perspective View of a block of material the preparation of which constitutes the first step in my method,

Figure 2 illustrates the second step of the method,

Figure 3 is a greatly enlarged end view of a slice of material cut from the block illustrated in Figures 1 and 2,

Figure 4 is a greatly enlarged end view of the subject matter of Figure 3 following the third step in the process, and

Figure 5 is a greatly enlarged end view of the finished grid, broken in several places for the sake of space, following the fourth and final step of 50 my process.

It should be said, for the sake of the record, that the drawing forming a part hereof, in the major portion, has been considerably magnified for purposes of clarity since in actual practice the 55 finished grid may well be less than one-eighth as sheet cork, celluloid, or other like material,

are secured together in the form of a block H, by intervening thinner sheets or layers l2 ofan X-ray impermeable material such as leadfoil coated with an adhesive or cement mixed with finely divided lead particles. By naming specific permeable and impermeable materials I do not wish to be understood as limiting myself thereto since I am appreciative of the fact that there are many materials having the desired characteristics which may be eiiicaciously combined in. the forms illustrated and described herein.

The relative thickness of the sheets of permeable material to the impermeable substance is approximately ten one-thousandths to one onethousandth, respectively.

The sheets of permeable and impermeable material, In and I2 respectively, are arranged alternately in layers and adhesively joined together to form a block I i (see Figure 1).

The next step in the process consists in cutting curved slabs or slices i l from the end of the block of Figure 1, as indicated by the dotted lines l3. Any conventional cutting means will be satisfactory for this purpose such as for example a bandsaw or extremely fine edged knives. The curves of these cuts are modified catenaries containing the necessary potential focal properties. Figure 3 is an end view of such a slab, magnified to clearly show the alternate thickness of permeable and impermeable materials. The elements forming this slab are parallel to each other although the mass of the same, that is the slice or slab, is curved.

The next step in the method consists in flattening the curved slab of Figure 3 to the form shown in Figure l. The elements of the slab are now convergent to a focal point at a selected position above and parallel to the surface of the slab and at right angles to the end shown. In other words the planes of the elements of the plate at this stage are concurrent at a line parallel to the surface of the plate at a determinable distance above it.

The fourth and final step in the process consists in polishing and otherwise preparing the slab illustrated in Figure 4 and the binding thereof as illustrated in Figure 5. To the top and bottom surfaces of the slab M, thus prepared, I apply .a coating orsurface E5 of an X-ray permeable material such as shellac, celluloid or the like and the edges thereof are bound with a frame 16 of metal or some other suitable material for the protection of the grid.

It will be appreciated from the foregoing description and Figure 5 of the drawing that the true focal efiect of the X-ray permeable elements in my grid is that they are progressively angularly different and are therefore capable of transmitting the direct or primary rays of the source of radiation while the intervening impermeable elements will absorb secondary radiation. Due to the extreme thinness of the permeable and impermeable elements in my grid, thus arranged, it will be instantly appreciated that my grid is capable of producing prints of a desired fineness of grain. Furthermore, the use of my grid will attain perfect focus and it has the great additional advantage of being flat and thus susceptible of use in those cases wherein it is desired to place the X-ray plate close .to the object or body being photographed.

Having thus described my invention that which is claimed and sought to be desired by grant of Letters Patent is:

1. The method of making a grid for X-ray photography which comprises the steps of first preparing a block of sheets of X-ray permeable material with intervening layers of X-ray impermeable material, next cutting curved slabs from the end of the block, and then flattening the individual slabs.

2. The method of making a grid for X-ray photography which comprises the steps of first preparing a block of sheets of X-ray permeable material with intervening relatively thinner X- ray impermeable material, next cutting curved slabs from the end of the block, and then flattening the individual slabs.

3. The method of making a grid for X-ray photography which comprises the steps of first preparing a block of sheets of X-ray permeable material with intervening layers of X-ray impermeable material, next cutting curved slabs from the end of the block, then flattening the slabs and finally covering the top and bottom surfaces of the flattened slabs with an X-ray permeable material.

4. The method of making a grid for X-ray photography which comprises the steps of first preparing a block of sheets of X-ray permeable material with intervening layers of X-ray impermeable material, next cutting curved slabs from the end of the block, next flattening the slabs, then covering the top and bottom surfaces of the flattened slab with an X-ray permeable material and finally binding the edges of the grid thus formed.

ANTONY P. FREEMAN. 

